Curiosity Sleeps Through Solar Flare

BY Jenny Marder  March 8, 2013 at 1:00 PM EDT

graphic-animation.jpgThis animation shows the path of the magnetic field that was discharged from the sun causing the Curiosity team to power down the rover this week. The modeling was carried out at the NASA Goddard Space Weather Research Center.

Earlier this week, when a large cloud of hot plasma erupted from the sun, and began charging across space toward Mars at speeds of 1,200 miles a second, the Curiosity team powered down the rover.

On NASA’s scale of solar flares, this one was “significant,” said Michael Hesse, director of the Heliophysics Science Division at NASA’s Goddard Spaceflight Center. And the scientists didn’t want to take any chances. So for 22 hours, while the coronal mass ejection hurled through space, Curiosity slept.

And the team, on behalf of the rover, tweeted this:

A coronal mass ejection, or CME, is a ball of magnetic field packed with charged particles that detaches from the sun and races through space, kind of like a traveling space blob, carrying with it increased radiation.

“High energy particles can impact electronics,” Hesse explained. “It can cause erroneous commands. When such an event is in progress, it’s prudent to be cautious.”

The rover’s handlers weren’t too worried though. The equipment is what’s called “hardened,” built to withstand high-energy particles and radioactive material.

The solar flare followed a glitch last week in the Mars rover’s memory, which prompted the handlers to power down its primary computer system and switch to the backup computer.

Lacking a dense atmosphere like Earth and a strong magnetic field, the Mars surface, like space itself, has little protection from radiation. A personal laptop, if taken into space, would get immediately fried, said Richard Cook, project director for the Mars Science Laboratory, the Curiosity rover mission.

In the case of the rover, the computer is protected inside of a lead box, and the parts themselves are built out of materials designed to withstand solar events, Cook said.

“If electronics are upset, we power them off and they’re fine,” Cook said. “On Earth, you have a battery and you zap it with a high-energy particle, and it blows up. And you ruin it.”

Radiation is even more powerful in other areas of space, like Jupiter or the Van Allen radiation belt, where a thick belt of charged particles released by the sun get trapped in the Earth’s magnetic field. Engineers must go to extra lengths to armor equipment that travels to these locations. Surrounding electronics in a vault or a shield of lead is one strategy. Lead absorbs high-energy particles. NASA’s Van Allen probes are shielded in thick aluminum, for example.

And if humans are ever sent to Mars, the walls of their spacecraft will have to be well armored from the sun’s radiation, and any habitat will likely be built underground. One surprising proposal to protect against cosmic rays is to line the spacecraft walls with water, food and human waste, according to this New Scientist article.

“Water is a very effective shield,” Cook said. “If you use water on the walls of the spacecraft, it has almost the same effect as lead.”

QUICK BITES

  • In this gripping and fascinating story, Eliza Strickland writes of a new sequencing machine that will soon enable researchers to decode an entire human genome for a low-cost $1000. Strickland opts to sequence her own DNA in the machine and have it analyzed.

  • In search of what sets today’s global warming apart, scientists have built a record of global temperatures that go back to the end of the last ice age — about 11,000 years ago — when mammoths and saber-tooth cats roamed the planet. NPR reports.

  • The Methuselah star, the oldest star in the galaxy, has been dated, and its older than the universe’s calculated age of 13.8 billion years. Huh? From the Hubble Site. But a new study is clearing up the strange paradox, reports Space.com.

NOT SAFE FOR LUNCH

  • It is not every freshwater turtle that is able to survive days in salty water. How do Chinese soft-shelled turtles do it? They pee from their mouths. Discover magazine reports that in this hostile environment, the salt would overwhelm turtles’ kidneys if not for their ability to discard toxins through their mouths.